Quote:
Originally Posted by island911
I've had a 3-D scanner for years. Let me strongly suggest you not mess around with digitizing your sculptures. It's a real PITA to get a 3D model of swoopy surfaces that can be 'played with.'
...It's one of those things that sounds cooler than it actually works out to be.
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I will strongly second this assessment.
We first put a toe in the digital ocean way back in the mid to late '80's, designing our first airplane parts in CATIA V2 R2. I well remember the first part model we NC machined from one of our datasets; we all stood around it in utter amazement, like the apes around the monolith in
2001. Prior to that day, all contoured surface models were developed by splining plaster between carefully shaped and positioned profile templates; work done by highly skilled model makers. The end product of their labors were very much "art" - very precise "art".
Well, we soon ran into problems mating digitally defined parts with template and plaster defined parts. So, the obvious thing to do was to go in and scan our older plaster models and create digital models of them. That's where the fun started...
In the digital world, surfaces are built from intersecting curves, and those curves are defined by equations. Anything from simple straight lines and constant radius curves to splines defined by 30, 40, or more degree polynomials. Even with that degree of freedom, however, digital curves are no match for a guy with a french curve. And therein lies the problem.
Curves drawn by hand on vellum, then translated onto aluminum templates (filed in by hand to match those curves) defy mathematical definition. We would gather points along a given vector when we "scanned" (with a CMM, laser tracker, faro arm, and some other equipment), then try to drive a spline through those points. Absolutely impossible to do that when constrained to some sort of mathematical definition, no matter how many degrees of polynomial your given system could crunch.
So, we tried the "point cloud" approach just to store the data. The simplest surfaces wound up with a "brazillion" points and were so data heavy we could not manipulate them. Much less machine anything to a point cloud at least to the level of accuracy and smoothness we required.
Anything hand made will encounter these same issues when attempting to digitize it. Granted, one may be satisfied with current accuracy levels for sculptures and replacement body parts, but we just couldn't make it work in our biz. Turned out to be far quicker, cheaper, and more accurate to start anew from a blank sheet. Or screen...